Aim of this study was to investigate heart valve calcification process by different biomineralogical techniques to provide\nmorphological and chemical features of the ectopic deposit extracted from patients with severe mitral and aortic valve stenosis,\nto better evaluate this pathological process. Polarized light microscopy and scanning electron microscopy analyses brought to light\nthe presence of nodular and massive mineralization forms characterized by different levels of calcification, as well as the presence\nof submicrometric calcified globular cluster, micrometric cavities containing disorganized tissue structures, and submillimeter\npockets formed by organic fibers very similar to amyloid formations. Electron microprobe analyses showed variable concentrations\nof Ca and P within each deposit and the highest content of Ca and P within calcified tricuspid aortic valves, while powder X-ray\ndiffraction analyses indicated in the nanometer range the dimension of the pathological bioapatite crystals. These findings indicated\nthe presence of highly heterogeneous deposits within heart valve tissues and suggested a progressive maturation process with\ncontinuous changes in the composition of the valvular tissue, similar to themultistep formation process of bone tissue.Moreover the\nmicrometric cavities represent structural stages of the valve tissue that immediately precedes the formation of heavily mineralized\ndeposits such as bone-like nodules.
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